City map of ancient Epomanduodurum (Mandeure - Mathay, Franche-Comté, eastern France) : contribution of geophysical prospecting techniques.

International audienceThis study presents the main results of the geophysical survey of ancient Epomanduodurum, at Mandeure-Mathay, Eastern France. In northeastern Gaul, Epomanduodurum is a site of a major scientific interest for the understanding of past settlements and territorial formation at the end of the Iron Age and during the Roman period. The site, including a Roman urban centre and two suburbs containing workshops, occupies more than 500 ha inside and beyond a meander of the River Doubs. From the beginning of survey in 2001, several methods (fast electrical imaging automatic resistivity profiling system, ground penetrating radar, magnetic and electromagnetic mapping) have been performed on a large scale in order to precisely identify the vast extent and structure of the Roman town. The interpretation of the geophysical data was carried out using a combination of different data sources, including ancient maps and excavations recently conducted on restricted areas. The overall organization of an artisan quarter of 8 ha was revealed along a main Roman road leading to the left bank of the River Doubs. On the other bank, a river fortification and a vast monumental religious complex were recognized in the southern part of the Roman town. The geophysical imaging shows that the sacred area includes several temples or groups of temples radiating from the theatre. Other new buried structures probably corresponding to annexes, chapels and altars were also detected within this sacred area of 10 ha bound on three sides by a wall enclosure with monumental passages. In a surveyed area of 70 ha, geophysical prospecting techniques provided a clear overall image of the Roman urbanism revealed through a rectangular road network and street system delimiting insulae of variable sizes. The detection along the River Doubs of buildings similar to storehouses attests to fluvial transport and also suggests the likely existence of a port. More generally, the combination on a large scale of geophysical prospecting, aerial photographs and excavations allowed a new plan of the urban structure of the ancient town of Epomanduodurum to be produced for an area of over 300 ha